1. Technical Field
The present invention relates to saltwater intrusion into fresh water bodies. More specifically, the present invention relates to methods and apparatus for a saltwater intrusion prevention system typically utilized at the interface of a fresh water body with a saltwater body to prevent the incursion of saltwater into the fresh water body.
2. Background Art
The prior art is directed to methods and apparatus for preventing the incursion of saltwater into freshwater bodies.
The intrusion of ocean saltwater into fresh water bodies through man-made structures such as ship channels, drainage channels, and navigation canals typically involves a process by which seawater migrates up-stream into and through the fresh water body. It is noted that seawater has a higher density than fresh water. In the case of a navigation canal, it is noted that the canal can have one or more canal locks that connect the fresh water body with the saltwater body. Each of the canal locks are flooded with water to enable a water craft to travel between the fresh water body at a first elevation and the saltwater body at a second elevation. The terminal ends of each canal lock include lock chamber doors. The seawater migration process occurs when the lower chamber doors of a canal lock are opened to the ocean. Under these conditions, the denser saltwater current displaces the lighter fresh water as it flows into the lock chamber wherein the saltwater is trapped upon closure of the lock chamber doors. This process repeats itself as successive lock chambers are opened and closed during the operation of the canal lock until the seawater has reached the source of fresh water. As a result of this process, the fresh water body insidiously becomes brackish overtime causing significant changes in the ecosystem and creating a serious threat to the water quality of the fresh water body.
In addition to the intrusion of the saltwater into the fresh water body, other problems exist that contribute to the deterioration of fresh water bodies. In tropical regions, annual precipitation is typically high and thus fresh water bodies regenerate during the rainy periods. This ensures that the water level remains relatively high and also serves to reduce pollution in the fresh water body. Often, the fresh water body functions not only as a navigation canal but also supplies water used for farming, public utilities, drinking, bathing and the like. Because of recent global conditions, rainfall levels have fallen off. Further, it is predicted that rainfall levels over the next fifteen years will be unseasonable low. This condition will, of course, result in less water to replenish fresh water bodies. In additional, operation of the canal locks results in a substantial loss of water each time the lock doors are opened and closed. For example, when the lower lock doors are opened to the saltwater body, literally thousands of gallons of fresh water can escape to the saltwater body. This problem is significant since, in some cases, the number of water craft traversing the canal between the fresh water body and the saltwater body is reduced.
Unfortunately, in certain fresh water bodies, portions are dead or dying with vegetation growth. As a result, bacteria feeds on the vegetation reducing the oxygen level in the fresh water body. Further, waste water and chemicals that are injected into the fresh water body increases the bacteria level and this in combination with reduced flow of fresh water destroys the ecosystem resulting in the death of all marine life in the fresh water body. In tropical climates, fresh water bodies normally rise and fall several times annually. This natural flushing serves to minimize the pollution of the fresh water bodies. When there is a large temperature differential between two bodies of water, clouds will form and rainfall is plentiful. For example, the water temperature of the Atlantic Ocean in the Caribbean area (i.e., approximately 85 degrees Fahrenheit) is typically warmer than the water temperature of the Pacific Ocean in the same area. Consequently, annual precipitation is typically plentiful in this geographical area of the world. However, the forecast of lower precipitation levels in the future is based upon the discovery that the water temperatures of the Atlantic and Pacific Oceans are equalizing. This determination has been made based upon the fact that the water temperature of the Pacific Ocean in the Caribbean region is increasing due to volcanic activity on the floor of the Pacific Ocean. Consequently, the level of pollution in fresh water bodies may not be controlled by the natural flushing process in view of the forecast of lower annual precipitation in many areas of the world.
The preceding problems set forth above create a bleak picture for the survival of fresh water bodies. The intrusion of saltwater from the oceans into fresh water bodies converts the fresh water environment into a brackish (ocean salt) environment destroying the natural flora and marine life. The pollution of fresh water bodies also occurs from the injection of waster water and chemicals and the increased growth of vegetation in the fresh water bodies resulting in increased bacteria levels and reduced oxygen levels therein. Additionally, the forecast of lower precipitation levels resulting from the equalizing of the water temperatures of major saltwater bodies, i.e., for example, the Atlantic Ocean and the Pacific Ocean, reduces the likelihood that pollution levels will be controlled by the process of natural flushing. Finally, fresh water is also lost during each operation of the doors of the canal locks.
Thus, there is a need in the art for a saltwater intrusion prevention system typically utilized at the interface of a fresh water body with a saltwater body to (a) increase the supply of fresh water to the fresh water body by employing a lock water recovery subsystem, (b) divert a portion of the water recovered by the lock water recovery subsystem for providing a saltwater intrusion barrier at the interface of the fresh water body and the saltwater body, (c) improve the quality of the fresh water returned to the fresh water body by filtering, aerating and chemically treating the recovered fresh water, and (d) further filter and chemically treat the recovered fresh water at a potable water treatment facility to provide potable water for drinking, bathing, agricultural and utilitarian use.